Recently, microencapsulated phase change materials have been described as a suitable component for substrate coatings when exceptional heat transfer and storage capabilities are desired. In particular, U.S. Pat. No. 5,290,904 for "Fabric with Reversible Enhanced Thermal Properties" to Colvin, et al. teaches that substrates coated with a binder containing microcapsules filled with energy absorbing phase change material enables the substrate to exhibit extended or enhanced heat retention or storage properties.
Research has demonstrated that applying a binder containing microspheres of phase change materials with commercial coating equipment can be problematic. It has been found to be especially difficult to maintain the durability, moisture vapor permeability, elasticity, flexibility, softness and weight of coated substrates when the coating is loaded with a sufficiently high content of encapsulated phase change material. More particularly, when an acrylic compound is used as a binder in which microencapsulated phase change material is disbursed is applied to a fabric and cured, subsequent product durability may suffer. The finished product may be susceptible to cracking or flaking. Deeper penetration of the coating compound into the base substrate may be attempted in an effort to minimize cracking and flaking. While durability of the resulting product may be satisfactory, the final product be unacceptably stiff.
Coatings of encapsulated phase change materials embedded in acrylic binders on elastic substrates are also problematical because elasticity of the finished product is compromised, and stretching of the coating can result in flaking of the coating. While substituting a latex binder for the acrylic binder alleviates some of the elasticity loss and flaking experienced with acrylic binders on elastic substrates, loading of the latex binder with a decreased amount to encapsulated phase change material may be required. To compensate and apply the desired amount of encapsulated phase change material, an increased amount of latex binder may be applied. However, this solution tends to reduce the flexibility expected to be achieved with a latex binder. The thicker latex coating may also have the effect of reducing moisture permeability and increasing tackiness of the finished product.
It is against this background that the significant improvements and advancement of the present invention have taken place in the field of substrate coatings containing energy absorbing, temperature stabilizing phase change materials and methods of manufacturing same.